Abstract

BECHER QUINODOZ, Fátima Noelia  and  BLARASIN, Mónica. T. Assessment of geomorphology-groundwater quality relationships using statistical techniques and numerical models in the sandy plain of the south of Cordoba, Argentina. Geoacta [online]. 2016, vol.41, n.2, pp.1-16. ISSN 1852-7744.

The area studied, located on the sandy plain of the South of Cordoba, is a palimpsest resulting from the juxtaposition of the Aeolian (“Pampean Sand Sea”) and the Río Quinto river systems. The area has an undulated topography, with old longitudinal dunes and modern ones resulting from reactivations by present winds. Paleochannels, belonging to the Rio Quinto river, and temporary and permanent lagoons were observed. Given the complexity of this environment, the objective of this work is to characterize the unconfined aquifer from a dynamic and geochemical point of view, establishing relationships with geomorphological features. A multivariate statistical analysis was made for the validation of the conceptual model. The unconfined aquifer presented a complex geochemical pattern with fresh and salt water (0.4 to 10.0 g/L) and sodium bicarbonate to sodium chloride geochemical type. There are also many samples with mixed anionic type. The Q mode multivariate analysis showed two groups: G1 explains fresh groundwater located in the fluvial-aeolian area and G2 represents brackish - salty groundwater in the fluvial (G2a) and aeolian (G2b) environment, respectively. Brackish-salty water is the result of regional flows and the fresh water is related to local flows and precipitation recharge in dunes. Furthermore, the conceptual hydrogeologic model was validated by numerical modeling, indicating that the geochemical processes (mainly dissolution of salts and cation exchange) may explain the geochemical evolution of water throughout a regional flow line, from the peri-mountain sector to the study area. Fresh groundwater of sodium bicarbonate type located in dunes sectors can be explained through the geochemical evolution of the rainwater that enters the aquifer where dissolution of salts and cation exchange take place.

Keywords : Modeling.

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